It is often desirable for marine research or other purposes to attach a tag, such as a visual or signal emitting tag, such as a sonic tag, into a large fish, such as a bluefin tuna or shark. Typically, tags have been inserted by first catching the fish with a rod and reel, and then inserting the tag; however, this approach is not wholly satisfactory, since the fish undergoes stress, may be injured, and may not survive the tagging procedure.
It is therefore desirable to provide a fish tag harpoon and method for tagging free-swimming fish to reduce stress on the fish.